Method of surface pretreatment before selective epitaxial growth

Abstract

A method of surface pretreatment before selective epitaxial growth is provided. A semiconductor substrate having metal-oxide-semiconductor devices formed thereon is provided, and a lightly dry etching process with a carbon-free plasma source is performed to remove a portion of the semiconductor substrate. Then, a selective epitaxial growth process is performed to form a semiconductor layer on the semiconductor substrate. A clean surface for selective epitaxial growth is provided by the lightly dry etching process, which can resolve the undercut issue and surface roughness.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method of surface pretreatment in a semiconductor process, and more particularly to a method of surface pretreatment before selective epitaxial growth process. [0003] 2. Description of the Prior Art [0004] As semiconductor devices are scaled to smaller dimensions, generally in the sub-0.1 μm region, it is highly desirable and generally necessary to fabricate such devices with source / drain shallow junction. However, when a silicide is formed on the source / drain region, the silicide easily contacts with the shallow junction to make junction leakage. Therefore, an approach to resolve the leakage problem is to use raised source / drain. Since the raised source / drain is formed upward above the substrate, the silicide could not easily contact with the shallow junction, and then the junction leakage can be reduced. [0005]FIG. 1A to 1B shows various steps for forming a conventional N-channel...

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Benefits of technology

[0012] The present dry etching process can effectively remove native oxide on the semiconductor substrate, and hence p

Problems solved by technology

However, when a silicide is formed on the source/drain region, the silicide easily contacts with the shallow junction to make junction leakage.

However, as shown in FIG. 1B, the surface pretreatment with strong acid leads to serious undercut

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